Counting Calories in your Homebrewed Beer

This week, I take a look at calories in your home brewed beer, how to calculate them and where they come from. With superbowl weekend upon us, the subject of how many calories are in your homebrew may be moot given the mountains of beer and snacks likely to be consumed on Sunday afternoon, but for those of you who are calorie or carbohydrate conscious, read on.

Calorie Counting

I’ll start with the good news first – an average 12oz commercial beer has slightly less calories than a comparable soda or even a glass of juice. An average American lager (say Budweiser at 5% ABV) has about 145 calories for 12 oz. A Coke classic runs about 155 calories for a 12 oz can and orange juice is about 184 calories.

If you drink light beer, they generally run from 100-112 calories per 12 oz and have slightly less alcohol (average of about 4.2% alcohol), placing them well below regular sodas or juice. Premium beers run a bit heavier – a Sam Adams Lager or Boston Ale has about 160 calories and high alcohol beers like New Belgium Trippel (7.8% alcohol) contain 215 calories in a single 12oz serving.

Where Do The Calories Come From?

Not surprisingly the calories in beer comes from alcohol and carbohydrates – both from the malted barley (or other grains) used to brew beer. During fermentation, yeast breaks down the simple carbohydrates and converts them into ethanol (ethyl alcohol). The longer chains of carbohydrates that the yeast cannot break down remain in the finished beer, contributing additional calories. Full bodied and all malt beers tend to have more residual carbohydrates. Roughly 60% of the calories in an average beer come from alcohol and 40% from residual carbohydrates.

Despite the term “beer belly”, very little of the alcohol you consume is converted into fat. In fact, your liver converts most of the alcohol into acetate which is then released into your bloodstream and consumed directly to produce energy. The bad part is that when your body is burning alcohol/acetate, it is not burning fat, so you will tend to retain the fat you already have, plus your body may convert some of the residual carbs from the beer into fat.

Adding to the effect is the fact that alcohol tends to be an appetite enhancer – so if you drink a lot you will likely eat more than you would with water or even other carbohydrate drinks. Not that all news is bad – in fact several studies have found that drinking in moderation (1-2 drinks a day) can actually have a positive effect on overall health if combined with a healthy diet and exercise. However, clearly moderation is the key.

Calculating Calories

Calorie conscious brewers can estimate the number of calories in 12oz of homebrewed beer from the starting (OG) and ending (FG) gravities. BeerSmith also will show you the calories if you use the Alcohol/Attenuation tool.

Total calories – just add the Calories_from_alcohol to Calories_from_carbs

So lets look at a sample beer with a OG of 1.048 and a FG of 1.010 which has 4.9% alcohol by volume. Running the numbers above, we get 99 calories from alcohol and 59 calories from carbohydrates, for a total of 158 calories. Most beers have calorie counts in this range – with the bulk of calories coming from alcohol and not carbohydrates.

Light and low-carb beers tend to be made at lower alcohol levels, and also have less malt and more adjuncts (corn, rice, etc) to reduce residual carbohydrates. Essentially light beer makers attack the problem on both sides – by cutting the alcohol levels and also cutting the residual carbs. Corn, rice and other non-barley adjuncts tent to ferment more fully leaving less residual carbs. The tradeoff is that the body of the beer comes from the residual carbs, so light beers made with more rice will generally have less body than barley malt beers. However, in very light bodied styles like American Pilsner, the effect is less noticed than it would be in a low-cal Porter or Pale Ale.

Brad,
Do these formulas hold up for beers with original gravity? I’ve compared calculations yielded by your equations with other methods found online (most notably here: http://www.mrgoodbeer.com/carb-cal.shtml) and found that at they are relatively close at lower original gravities but your formulas start to yield significantly higher calorie counts at higher original gravities.